PAS Youth chief Mahfuz Omar said the station's practice of broadcasting selected parts of the party's ceramah was being done to give a misleading picture of the opposition party leaders.
Mahfuz was responding to a charge that PAS leaders are condoning and encouraging their members to use foul language.
He accused RTM of selectively airing a ceramah by PAS spiritual leader and Kelantan Mentri Besar Nik Aziz Nik Mat and fellow speaker Bunyamin Yaacob to paint the opposition party in a bad light.
"It is important for the viewers to see for themselves and make their own judgment over what have been said by the two speakers in their ceramah," Mahfuz said in a telephone interview.
"As long as RTM does not dare to show the whole footage of the ceramah, it appears that its intention is nothing but to mislead viewers."
Over the past week, RTM's TV1 has been airing footage of the opposition party's ceramah in which Nik Aziz had allegedly referred to Allah to as a samseng (thug).
Bunyamin was shown slandering Prime Minister Mahathir Mohamed of having watched pornographic video with his grandchildren.
Kelantan Umno chief Mustapa Mohamed claimed that PAS leaders were condoning and encouraging the use of foul language because the party needed to garner support.
The former second finance minister, who lost the Jeli parliamentary seat in the1999 general election, also claimed that PAS was resorting to indiscriminate interpretation of Quranic verses to gain public support.
He was reported as having questioned the ability of PAS leaders, particularly Nik Aziz, to lead the people when it was clear that they were using profanities which are against the teachings of Islam.
Mahfuz slammed the television broadcast as misleading as it did not show the speeches by the two speakers in their entirety.
He accused the station, which is under Information Ministry Parliamentary Secretary Zainuddin Maidin's supervision, of being more interested in slandering the opposition party than in delivering news.
"Therefore, I would like to challenge RTM to show the whole footage of ceramah, including Nik Aziz's spech, it wished to continue showing them," Mahfuz said.